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Explanation of Co-Witness

Now, I have around this business for a bit now, on both ends of the spectrum, from the .mil side to the industry side.

I think there is common misconception on what Co-Witnessing really is, as to a true definition. Now I am going to put it to the people without my 2 cents and see what the public says Vs what the operators and shooters tend to say (and I will say that there are Tier 1 Operators that do not agree also on this very topic).

This term is thrown around so loosely without a true "text book" definition.

So here it is:

Co-Witness is -

A - Having the ability to be able to align your Iron Sights or BUIS through your Optics / Red dots (where it locates in the glass it does not matter {middle / bottom 1/3}), leaving your red dot Zeroed.

B - Sighting in your Optics / Red Dots and then bringing your Iron Sights or BUIS to align with the Red Dots.

Each Warrior wants to leave the mark of his will, his signature, on important acts he touches. This is not the voice of ego but of the human spirit, rising up and declaring that it has something to contribute to the solution of the hardest problems, no matter how vexing!-Pat Riley

Brett-
No argument with you ... "but" ... what I normally hear folks say is that they've zero'd their irons and have now "co-witnessed" their optics/red-dots/etc to their irons or visa-versa.
I take this to mean that their Dots & Irons will be POI/POA together.

... make sense?

My default is quite different .... my Dot is where it is; my Irons are where they are - because they are different systems.

I zero seperately and then check. If they align I'm good to go. So far they've always aligned, so I'm not sure what I'd do if they didn't.

I tend to use "co-witness" to verify that the sights and dot are both still zeroed. If I pick up the gun and look through the iron sights and optic at the same time and find that they line up, chances are about one in a million that they both got knocked out of alignment to the exact same point.

At the end of the day though I'm not sure that it matters what you call it or what you use it for as that's really just a matter of semantics and personal preference.

I am relatively new to optics on anything. I keep thinking my eyes are young enough to still use irons (on that account, I am mistaken). Anyway, what Erick says is the way I understand it, regardless of whether the top of the front sight post and your red dot are visually coincidental, or located in different quadrants/thirds/whatever of your field of view.

I do the zeroing backwards from you guys. I zero with irons, then put the dot on top of the front sight post, almost like a boresight. I then shoot just optics to verify or set the optic to shoot same POA/POI as the irons.

I've always considered "co-witness" to indicate that the optic's red dot is co-located with the aligned sight picture, that is, your red dot is on top of your front post when the sights are aligned.

Co- means together, and witness is a reference to what you see, and I take co-witness to mean that your sighting indicators (aligned sights and red dot) are together (in the same place).

My irons and my EOTech do not co-witness, because I run a LaRue EOTech riser. Of course, I can still use my irons through the EOTech window, but my aligned sight picture is not in the same place the red dot is.

I'm not calling anyone else wrong, just explaining how I use the term.

A - Having the ability to be able to align your Iron Sights or BUIS through your Optics / Red dots (where it locates in the glass it does not matter {middle / bottom 1/3}), leaving your red dot Zeroed.

B - Sighting in your Optics / Red Dots and then bringing your Iron Sights or BUIS to align with the Red Dots.

Option A is what I refer to when I use the term "co-witness." It just means that you can align your front and rear iron sights though the optic, should the optic fail, eliminating the need to remove it in order to transition to irons. Normally, the irons would sit in the lower 1/3 of the FOV.

Option B is something I have heard referred to as "absolute co-witness" in order to distinguish it from Option A.

Like Erick said, my dot (or reticle) is where it is and my irons are where they are, because they are different systems. I zero the two separately. If I'm using an optic (in my case an EOTech + LaRue mount) the iron sights might as well be invisible to me. I should be seeing only on the reticle and the target. If I am using irons, the optic is either off the weapon or inoperable, so there is no reticle in my FOV. That approach seems to work for me, but I have limited experience and am a long way from being an expert. If I am mistaken or misinformed, please let me know.

I do the zeroing backwards from you guys. I zero with irons, then put the dot on top of the front sight post, almost like a boresight. I then shoot just optics to verify or set the optic to shoot same POA/POI as the irons.

This is how I do it also. It seems a lot easier to bring the dot to the irons, than the irons to the dot.

This is how I learned it: Co-witness is being able to align one's iron sights through the optical window, the two common setups being "Absolute" co-witness (recticle centered in optic, irons centered in optic) and "lower third" co-witness (iron sights are visible in the bottom of optical window, when recticle is centered, irons will be below the recticle and less intrusive to sight picture). With the commonly co-witnessed sights like Aimpoint and EOTechs, the dot will still align (enough for social purposes) with irons when you change your line of sight to take the iron sight picture, because they are (mostly) parallax-free. Alignment is assuming the optic and irons are sighted in for the same POA/POI, but that isn't a requirement (although I don't know why you wouldn't).

The whole point is that if the optic were to fail, and you suddenly had no recticle, then your irons would be visible through the optical window and the transition would be as quick as possible without a drastic change in head positioning or needing to manipulate anything mechanically.

--Josh H.
Zombies seek out and eat brains. Don't worry; you'll be safe if they attack.

Argument to that is this:
Iron Sights and Red dots DO NOT print the same on a 25M zero target so if you adjust them separately @ 300m your will not have the same POA/POI. (This is why SOPMOD has offset Targets)

Iron Sights Should naturally co witness, so the term does not apply if optics / Red Dots are not being used as a 3 part alignment. (Rear sight to Red Dot to Front Sight Post)

Argument to this:
Well, I just want to be able and see them through my optic / red dot and thats why they call use that term, and it sounds better.

Each Warrior wants to leave the mark of his will, his signature, on important acts he touches. This is not the voice of ego but of the human spirit, rising up and declaring that it has something to contribute to the solution of the hardest problems, no matter how vexing!-Pat Riley